Tampering and theft of valuables and/or goods while in storage or transit is a problem for many industries and forms of transportation. Whether transported by land, air, or sea, vulnerability to theft as well as tampering by smugglers, terrorists, and stowaways is a persistent concern for shipment providers, customers of such providers, recipients of shipments, and others involved in such processes. Historically, cargo shipments have been particularly attractive targets for such tampering activities, thus placing them at greater risk of intrusion or compromise.
To adequately address these risks, cargo security measures must simultaneously provide solutions that are reliable, cost-effective, and easy-to-use, in order to achieve mandated security levels without impeding legitimate trade and commerce. This is a highly challenging prospect considering the sheer volume of cargo to be screened and secured and the sheer size of containers and/or shipments to be transported. In 2007, 3.8 million tons of cargo was transported on U.S. passenger flights. 56% of this cargo was transported domestically and 44% was transported on flights to the United States. In fiscal year 2008, the number of cargo containers imported to the U.S. was 9.8 million.
The challenges upon cargo security are further exacerbated by the complexity of the network that is involved in the transportation of cargo. Many different participants, handlers, and points of transfer are involved from start to finish. For example, taking cargo from a warehouse to a port/airport to a plane to a delivery truck to a final location may involve handling by the respective employees of four or five different businesses. Often, cargo is first transported to consolidators that combine shipments onto pallets, which are then packed into cargo containers or onto unitized load devices (ULDs) for aircraft. The containers and ULDs are then transferred to the actual carriers, who may deliver the cargo directly to its destination port or airport, or route it through one or more connections. At each point in this supply chain, the cargo is potentially vulnerable to tampering and theft.
One attempt to provide a cost-effective security system is the use of non-intrusive imaging (NII) technology that utilizes gamma radiation to screen cargo containers at several ports. However, radiation technology tends to create discomfort among operators of the equipment and drivers who are needed to pull the containers through the devices, given the potential and perceived health hazards associated with radiation exposure. Furthermore, for air cargo in particular, the expense and size of the X-ray or computed tomography (CT) equipment capable of scanning ULDs is cost prohibitive. ULDs can have dimensions of about 96″×125″×64″, or even as large as about 96″×238″×96″. Scanning devices capable of screening shipments this large are extremely expensive.
One attempt to provide a more affordable solution for cargo security has been to screen pallets and packages sent by shippers prior to consolidation, and then secure the container or ULD in a way that guarantees detection of any intrusions or attempts to tamper with the cargo in order to add illicit materials or remove merchandise. Especially for containers, numerous technologies exist for securing the container door(s) and monitoring the conditions within the container, including light intensity, temperature, pressure, humidity, and even magnetic flux, for indications of intrusion. Many of these technologies also include wireless networking capabilities for communicating status updates of the cargo and locking devices and for alerting personnel to any detected hazards in the container or opening of the door.
For air cargo ULDs, which are sometimes enclosed only by a plastic wrap (e.g., “pallet wraps”), fewer solutions have been proposed. Some ULD wraps with tamper-evident locking zippers have been developed. However, such current cargo security technologies lack the ability to sufficiently and simultaneously address tamper-detection reliability, affordability, and ease-of-use.
Alternatively, some attempts have involved rapidly producing a vacuum that is sufficient to vaporize particular substances disposed within the internal chamber of a container to be shipped prior to sealing the container. Such systems typically can require high volume vacuum pumps and other expensive equipment. Additionally, vaporization pressures vary from substance to substance, thereby limiting the types of particulates that will be detected as a result of the applied vacuum. If such systems are intended to be used for a broader range of substance detection, calibration may be required prior to applying the vacuum so as to select a particular substance or group of substances that will be vaporized by the vacuum.
An additional drawback of such systems is that the vaporization pressure of many substances is extremely low, e.g., on the order of 10−7 mm Hg. Requiring a vacuum on this order of magnitude can impose extremely strict limits upon the suitable materials, etc. for constructing containers capable of enclosing such vacuums. Additionally, vacuums on this order of magnitude can cause substantial harm to the contents being tested, thereby producing additional required packaging for the contents being tested prior to conducting the detection tests. Systems and methods constrained by such pressure requirements either impose strict packaging requirements to endure the extremely low vacuum conditions, or are associated with impractically long wait times for vaporization to occur at less extreme vacuum pressures. Additionally, high volume pumps sufficient for pumping large volumes to these pressures are also cost-prohibitive given the quantity of goods that must be screened and shipped daily.